Understanding the d100 Table in Dungeons & Dragons 

Discover how to use the d100 table in Dungeons & Dragons to enhance your gameplay. Learn about the mechanics and potential outcomes of rolling (on) a d100 in D&D. 

Understanding the d100 Table in D&D

The d100 table is a staple in D&D games. They give the GM a chance to straightforwardly create unique encounters or rewards, respond quickly to unexpected player questions or character actions, and add some interesting or unusual meat to the bones of a standard situation. Indeed, a search for “d100 table” brings up hundreds of examples of what GMs are using themselves and what companies are providing to help enhance games. 

Many of these tables are straightforward lists that give each item an equal chance of occurring if d% dice are rolled, while others, such as the DMG Treasure Hoard and Magic Item tables are weighted so that lower-level results are more likely than higher ones. Some tables are simply basic lists (such as the Magic Item tables) while others give greater depth of explanation or a more detailed story element that broadens what might otherwise be a simple answer. 

What is a d100 in D&D?

It is important to remember that while a d100 or other dice combination are being used to represent the percentage chance of something happening–i.e. the likelihood of a result occurring if the die or dice are rolled 100 times–it maybe that you have 100 possible outcomes and you still want the lower-level results or less complicated to occur more frequently. In that case, you need that different dice combination that weights the results toward a particular range. Whatever you employ, you are aiming to be able to show there are a total of 100 possible outcomes. Of course, a d100 is the most straightforward choice, because what you roll is what you use! 

Mechanics of a d100 Roll 

The most common methods of rolling this percentage chance, or d% as it is often known, are either the d100, usually numbered 1-to-100, or using two 10-sided dice, with or without one of them having tens on it–10, 20, 30 and so on and the other with units–1, 2, 3, and up. Remember, each D&D edition invariably states that rolls of 00 and 0 equal 100, from the original D&D Monsters and Treasure book in 1974 all the way to page 6 of the D&D 5e Player’s Handbook. 

These two methods give each possible outcome an equal chance of appearing, and when a table has fewer than 100 entries, it usually means weighting occurs, with the low-level results appearing first on a list with their greater percentage chance. 

However, there are other ways to generate numbers from 1 to 100 and still get a weighting effect. Admittedly there is a little more calculation involved, but these methods do mean tables with 100 entries can be used in level-appropriate ways.

For example, rolling eleven 10-sided dice gives a total range of 11 to 110. If you then take 10 from the total, you get a range of 1 to 100 (so 11d10-10). Similarly, rolling nine 12-sided dice gives a range of 9 to 108, so then taking 8 off the total leaves you with that 1-to-100 range (9d12-8).

But with both these examples, the results are weighted toward the middle of the range, i.e. 50 and 51, so as a result, a d100 table with 100 entries should have its lower-level results positioned from the middle outwards, and its high-level results close to the extremes, 1 and 100. 

Other dice combinations also do this, such as (5d20+1d5)-5, (2d20+1d12+10d6)-12, (7d10+9d5)-15 or (9d8+12d4)-20, which produce the 1-to-100 range. While they look odd or complex even, their value lies in the fact that the more dice you roll, the more likely you are to get a mid-range result. This means a table with 100 entries can be used for parties of many different levels, just by rolling different numbers of dice. The lower the party level, the more dice you roll. The d100 – Grasslands Events and Encounters table is an example.

Understanding d100 Table Outcomes

The d100 table is used on many occasions in the core rule books, and their results tell us more than what is written down when we think about the entries. Consider the table for the wand of wonder. There are 22 entries, so we automatically know some MUST have a greater chance of occurring than others as 100 does not divide evenly by 22.

Next, when we look at the possible results, the two most likely results are, “You cast lightning bolt” (37-46) and “You cast fireball” (70-79), while the least likely is, “The target’s skin turns bright blue for 1d10 days” (96-97). Other bizarre effects have just a 3% chance of happening. 

This means that for every five times the wand is used, the table suggests one of them will be either lightning bolt or fireball, while chance states it will take 50 uses before a target is turned blue. To me, that seems to indicate that a wand of wonder can be primarily thought of as an attack item, so that any reason you introduce the wand might follow this guidance. 

Another example of weighting suggesting a path to follow is the alignment of sentient magic items. Again, 100 does not divide equally by the number of options, in this case the nine alignments, so they cannot all have the same chance of occurring.

When we look on the table, the alignment with the greatest percentage chance of occurring is Neutral Good (16-35) which means one in five sentient magic items are so aligned. The two least likely alignments are Lawful Evil and Chaotic Evil at just 4% each. To me, this suggests not only that NG items should be the ones appearing most often, but also that it may be the case that sentient items are unlikely to be owned by devils and demons. 

Incorporating d100 Rolls in Storytelling

Let’s think again about how a table entry can influence storytelling and ways that we might “read” entries in general by going back to that wand of wonder (Magic item Table G, 99).

While the wand can be found in a treasure hoard of any level, it is most likely to appear in one designed for Challenge 11-16. Straightaway this gives hints as to who or what is carrying it, or what the party will have to deal with to get it.

For instance, because of its position on the hoard table–in the final third–or the “percentage section”–in the final 25%–we might decide that it is more likely to appear in hoards suited to Challenge 15 or 16 (the higher ratings), and ignore it if it appears when we are putting together a reward for a Challenge 11 event.

As can be seen below, the wand can be a straightforward reward item for the party’s efforts or become part of a greater story that leads the characters further into their adventure: 

• We could just present the item by name and be done: 

• It could be broadly described, and a roll made to work out what it is, or research done to discover what it might do.
• It could be that it is in pieces–a gold handle, two-thirds of which is studded with rainbow-hued glass or gems and is decorated with gold filigree, while one-third is scored with a screw-like thread; three small tubes, each with an inner thread and arms (two, three, and four) that have spherical gem or glass beads on them; and a short gold spike, bearing a misshapen multi-sided gem, that slots into the end of the handle. Successfully building it and experimenting with the threaded tubes may bring a result. 
• The party discovers a stone statue of a half-elf pointing a wand at its left eye. Describe the wand, either broadly or using elements of the detailed “in pieces” entry above. 
• It could be that the characters enter a room and see a 30-foot-long line of 40 gems on the ground between the door and a dead gnome with leaves sprouting from it. Behind the gnome is a dead blue rhinoceros. The gnome and the rhinoceros look to have both been killed by lightning, if the lingering smell of ozone is anything to go by. 

Balancing d100 Outcomes for Fair Gameplay

Rolls made on d100 tables must always be balanced, unless there is a deliberate intention to either over-reward the party or show the characters that they face a stern test or foe. There is no harm in giving the players some leeway if they have rolled badly. As the DMG says (p.236), “dice are neutral arbiters” and it may be the case that ignoring a particular result or allowing the effects to take more time than might be expected, is perfectly reasonable.

Tables aren’t there to skew the game; they are there to make suggestions as to what might happen or what might be found. Using the result to enhance the game is key, as they should help players and characters become immersed in the world you have created.